The present invention relates to a type belt printer for use with an electronic desk calculator or the like, and more particularly to a printer which may eliminate an undue time in a printing operation to increase a printing speed.
FIG. 4 is a plan view of a conventional type belt printer. Referring to FIG. 4, a motor 2 is supported to a frame 1, and a pinion 4 is mounted on an output shaft 3 of the motor 2. Rotation of the pinion 4 is transmitted through a pair of idle gears 5 and 6 to a driving pulley 7. A type selector lever 8 is rotatably provided in the vicinity of the driving pulley 7. A pawl portion 9 of the type selector lever 8 is adapted to be engaged with the driving pulley 7 to stop rotation of the driving pulley 7. Further, an electromagnetic clutch 10 is provided in the vicinity of the type selector lever 8. When the electromagnetic clutch 10 is energized, the type selector lever 8 is rotated to engage the pawl portion 9 with the driving pulley 7.
The driving pulley 7 is exposed to one side of the frame 1, and a driven pulley 11 is exposed to the other side of the frame 1. As shown in FIGS. 5 and 6, a type belt 12 having a plurality of types 13 arranged in series is wound around the driving pulley 7 and the driven pulley 11.
A platen 14 supported to the frame 1 is provided in front of the type belt 12. A carriage 15 having a hammer 16 for hammering onto the platen 14 a desired type 13 of the type belt 12 on the platen 14 side is provided inside the type belt 12 in such a manner as to be laterally movable by a suitable mechanism (not shown). The carriage 15 is formed at its lower end with a pair of mask members 17 for preventing any two types adjacent to a desired type 13 of the type belt 12 from being printed when the desired type 13 is hammered by the hammer 16. The mask members 17 are formed by bending a support portion 17a horizontally integrally projecting from the carriage 15, and are supported like a cantilever by the support portion 17a. The mask members 17 are spaced from each other a distance substantially equal to a width of one type 13, and are located between the type belt 12 and the platen 14.
The carriage 15 is normally biased by a spring 18 so as to be returned to a home position under a free condition. A print paper S is supplied between the type belt 12 and the carriage 15 by a pinch roller 19 and a paper feed roller (not shown). An ink roll 20 for coating ink to the type belt 12 is provided in the vicinity of the driven pulley 11.
In operation, the rotation of the motor 2 is transmitted from the pinion 4 through the idle gears 5 and 6 to the driving pulley 7 to thereby rotate the driving pulley 7, which is followed by the rotation of the driven pulley 11 and the type belt 12. When the electromagnetic clutch 10 is energized, the type selector lever 8 is rotated to engage the pawl portion 9 with the driving pulley 7, thereby stopping the rotation of the driving pulley 7 and locating a desired type 13 at a position opposed to the carriage 15. Then, the hammer 16 in the carriage 15 is driven to press the type 13 onto the print paper S exposed in front of the platen 14, thereby transferring the ink coated on the type 13 to the print paper S. Thus, the printing operation at a first column is ended. Next, the electromagnetic clutch 10 is deenergized to shift up the carriage 15. Then, the above-mentioned printing operation is repeated for desired columns to complete the printing operation of one line. Thereafter, the carriage 15 is returned to the home position. Then, the driving pulley 7 is idled by a predetermined rotative amount without conducting selection of the type, and the print paper S is automatically fed by an amount of one line by the pinch roller 19 and the paper feed roller (not shown), whereby the printing operation of the next one line is ready to start.
In the conventional printer as mentioned above, the feeding of the print paper S is started upon completion of idling of the driving pulley 7 by the predetermined rotative amount after the end of the printing operation of one line. That is, since the conventional printer is designed to mechanically shift the printing operation to the paper feeding operation, the paper feeding operation is carried out after completion of idling of the driving pulley 7 by the predetermined rotative amount under the condition where the printing operation is not carried out. During printing operation of one line, while the driving pulley 7 is rotated once after the end of printing of a certain column, a type at the next column is selected to thereby reset the number of revolution of the driving pulley 7.
However, a time for idling the driving pulley 7 by the predetermined rotative amount is wasteful in view of a requisite printing time of the printer. In the case of printing plural lines, such an idling time causes elongation of the requisite printing time.